Massachusetts reports another EEE case, raising risk levels: 'Mosquito season is not over'

Another EEE case has been reported in the Bay State, raising the risk levels in several communities as health officials remind people to keep using bug spray and reschedule outdoor evening events.

The Massachusetts Department of Public Health on Thursday announced an additional human case of Eastern Equine Encephalitis (EEE) and one more human case of West Nile virus (WNV).

The region is facing a major outbreak of mosquito-borne diseases this season. Recently, a man in New Hampshire died from EEE.

Both of the new Bay State cases are men in their 70s. One man was exposed to EEE in central Middlesex County, bringing the total number of EEE cases in Massachusetts this year to three.

The other man was exposed to WNV in southern Middlesex County in an area already at high risk for the disease. This is the seventh case of WNV in Massachusetts this year.

“Today’s announcement of additional West Nile virus and Eastern equine encephalitis cases makes it clear that mosquito season is not over,” said Public Health Commissioner Robbie Goldstein. “It is essential that residents continue to use mosquito repellent with an EPA-registered active ingredient every time they are outdoors.

“We also strongly recommend that residents and towns in areas at high risk for EEE reschedule their evening outdoor events to avoid peak mosquito biting hours,” Goldstein added.

EEE risk levels are being raised to high in Acton, Ayer, Boxborough, Carlisle, and Littleton in Middlesex County; and Harvard in Worcester County.

The following communities are being raised to moderate: Bedford, Billerica, Chelmsford, Concord, Framingham, Groton, Lincoln, Shirley, Stow, Tyngsborough, Wayland, and Westford in Middlesex County; and Berlin, Bolton, Clinton, and Lancaster in Worcester County.

WNV risk levels in the following communities are being raised to high: Stoneham and Wakefield in Middlesex County.

EEE and WNV are transmitted to humans through the bite of an infected mosquito. The last outbreak of EEE occurred in 2019-2020 and resulted in 17 human cases with seven deaths.

There were six human cases of WNV and no animal cases in 2023. No animal cases of WNV have been detected so far this year.

“Mosquito behavior starts to change in September,” said State Epidemiologist Catherine Brown. “They will be less active during cooler temperatures. However, during periods of warmer weather, such as are being forecast for the end of next week, mosquitoes will be out and looking for their next meal.”

_____